Dual Fuel-Cell Drive Control for Battery Current Balancing
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Solution Overview
Problem
When two different drive units cooperate in parallel to drive an electric device using a shared AC-DC converter, the battery may be over-charged or over-discharged due to the lack of consideration for driving one electric device with different drive units.
Innovation Solution
A power supply control system that includes an electric device, an inverter, a first drive unit with a fuel cell system and a battery, a second drive unit with a fuel cell system and a battery, and a control unit that manages the current flow through both batteries to prevent over-charging or over-discharging by setting target current values and performing torque limit control when threshold currents are exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If one AC-DC converter is shared by two different drive units, then cost is reduced and device complexity is lowered, but the battery may be over-charged or over-discharged due to lack of coordination between drive units
Solution Approach 1:
The control unit continuously monitors the charge states of both batteries and adjusts the operation of each drive unit based on real-time feedback. When one battery approaches full charge or complete discharge, the control unit modifies the power distribution to prevent over-charging or over-discharging, ensuring reliable operation of the shared AC-DC converter system
Solution Approach 2:
The control unit dynamically changes operational parameters such as the target current values for each battery and the torque output of the motor based on the charge states. By adjusting these parameters in real-time, the system prevents battery damage while efficiently utilizing the shared AC-DC converter
2Productivity
If two drive units operate in parallel to drive one electric device, then power output and productivity are improved, but the battery current control becomes complex and may lead to over-charging or over-discharging
Solution Approach 1:
The control unit acts as an intermediary that coordinates between the two drive units. It receives current sensor outputs from both batteries, processes the charge state information, and generates appropriate control signals for the voltage converters and motor, simplifying the overall control architecture while maintaining safe operation
Solution Approach 2:
The control system is segmented into independent control loops for each drive unit, with each voltage converter controlling its own battery's current. The control unit coordinates these segmented loops by setting target current values, allowing each battery to be managed independently while contributing to the overall power output
3Ease of operation
If the first voltage converter controls voltage and the second voltage converter controls current, then each converter operates with simplified control logic, but coordination between them requires complex control strategies to prevent battery over-charging or over-discharging
Solution Approach 1:
The control unit uses feedback from current sensors to monitor the actual current flowing through each battery. Based on this feedback and the charge state of each battery, the control unit adjusts the target current values sent to the voltage converters, preventing over-charging or over-discharging while maintaining simple individual converter control logic
Solution Approach 2:
The control unit dynamically changes the target current parameters for both voltage converters based on battery charge states. When one battery is nearly full or empty, the control unit modifies the target current values to prevent extreme charge conditions, allowing simple voltage and current control at the converter level while ensuring battery safety
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively prevents over-charging or over-discharging of batteries in each drive unit, ensuring efficient operation and reducing costs by maintaining optimal battery states during parallel operation of the drive units.
Implementation Method 1
an inverter connected to the electric device to perform conversion from DC power to AC power
Implementation Method 2
a first voltage converter that controls a voltage of a DC-side terminal of the inverter
Implementation Method 3
a second voltage converter that controls a current in the inverter
Data Source
AI summary
A power supply control system includes: an electric device; an inverter; a first drive unit including a first fuel cell system, a first voltage converter, and a first battery; a second drive unit including a second fuel cell system, a second voltage converter, and a second battery; and a control unit that controls the inverter and/or the first fuel cell system so that a first current value flowing through the first battery reaches a target value of the first current value and controls the second voltage converter and/or the second fuel cell system so that a second current value flowing through the second battery reaches the target value of the first current value.